(a) Field of the Invention
The present invention relates to a process for the preparation of phenyl carbamate derivatives, useful in the treatment of CNS (central nervous system) disorders. The present invention further relates to a process for preparation of intermediates in the synthesis of the phenyl carbamate derivatives.
(b) Description of the Related Art
CNS (central nervous system) disorders nowadays concern large sections of the population. In particular on account of the increase in elderly people, the numbers of patients are increasing continuously.
Myotony or spasm, which is one of the CNS disorders, is frequently observed as a sequel of cerebrovascular disorders such as stroke or a sequel of head injuries, and is not easy to treat. Myotony or spasm is one of skeletal muscle dysfunction diseases due to an increase of muscle tone, and caused by central nervous system damage due to various causes such as external injury, cerebrovascular accidents, and the like. The muscle tension is caused by various causes, for example, cervicoomobrachial syndrome which is caused by abnormal posture, fatigue, age-related spine deformity, and the like, and causes spasticity or pain in skeletal muscles of the neck, shoulders, arms, waist, and back; spastic paralysis causing the disability of voluntary movement due to muscle hypertonia of hands and feet by disorder of central nervous system such as cerebrovascular disorder; and a combination thereof, thereby resulting in serious hindrances to normal life.
In particular, spastic paralysis is a serious disorder with accompanying symptoms including muscle tension and/or muscular stiffness of hands and feet, difficulty in walking, and the like, thererby causing serious hindrances to normal life. Centrally acting muscle relaxants relieve muscle tension by blocking receptors associated with the stimulation of muscular function or stimulating receptors associated with inhibiting muscular function, or reducing excessively activated reflex function.
Such centrally acting muscle relaxants may include Methocarbaamol, Chlormezanon, Carisoprodol, Eperisone, Phenprobamide, and the like. However, these drugs act on interneuron of the spinal cord, thereby inhibiting monosynaptic and polysynaptic reflexes, and thus, may cause side effects, such as central nervous inhibition, muscle weakness, and the like. Therefore, there is clearly a need for improved medication.